1. Field of the Invention
This invention relates to conveyor mechanisms, and particularly to a combination of a turn-around sprocket and an endless chain of conveyor elements which rides thereon, especially adapted for use in high rate of fire, ammunition handling systems.
2. Prior Art
Conveyor mechanisms in high rate of fire, ammunition handling systems are shown in U.S. Pat. No. 3,429,221 issued to R. C. Kirkpatrick on Feb. 25, 1969; U.S. Pat. No. 3,437,005 issued to J. M. Trumper on Apr. 8, 1969; and U.S. Pat. No. 3,670,863 issued to O. H. Meier on June 20, 1972.
In the system shown by Kirkpatrick, the conveyor comprises a sprocket and an endless chain of ammunition conveyor elements. Each element is substantially one half of a cylinder, cut along its longitudinal axis, so that it has a semi-circular concave inner surface to receive the case of the round, and a semi-circular outer surface to mate with one of a plurality of congruent cutouts in the sprocket. The sprocket may have two spaced apart plates with mutually aligned cutouts, both plates being fixed to a hub. Each element has a forwardly extending arm which is coupled to a rearwardly extending bifurcated arm of the next preceeding element, to form the articulated endless chain. The sprocket thus engages and positively drives each element in sequence. The pivot pins travel at a constant velocity both in the straight run and around the sprocket, thus maintaining a constant belt velocity. The centerline of travel of the rounds is spaced from the centerline of travel of the couplings between the elements. Typically, the round carried in the conveyor element, as it travels around the sprocket, is diverted by stationary guides from the respective element into another sprocket; i.e. a "hand off." As the round engages the stationary guides, it back loads the elements, and, since the sprocket cutouts and the element outer bearing surfaces are mating semicircles, there is a tendency for the element to rotate within the cutout within the freeplay permitted by the next preceeding and next succeeding elements, and any longitudinally extending guide feet. Such rotation is disadvantageous as it causes nonsynchronization between the handing-off element and the handing-in sprocket, and also causes accordioning of the preceeding elements in the chain. The nonsynchronization will result in the handing-in sprocket cutting into the case of the handed round. The accordioning may result in binding of the longitudinally extending feet of the elements in their guides.